Re: [RFC 05/10] nfsd41: callback infrastructure

["J. Bruce Fields" <bfields@fieldses.org>]

On Fri, May 01, 2009 at 02:06:08AM +0300, Benny Halevy wrote:
> From: Andy Adamson <andros@netapp.com>
> 
> Keep the xprt used for create_session in cl_cb_xprt.
> Mark cl_callback.cb_minorversion = 1 and remember
> the client provided cl_callback.cb_prog rpc program number.
> Use it to probe the callback path.
> 
> Define xdr sizes and code nfs4_cb_compound header to be able
> to send a null callback rpc.
> 
> Signed-off-by: Andy Adamson<andros@netapp.com>
> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
> [get callback minorversion from fore channel's]
> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
> ---
>  fs/nfsd/nfs4callback.c     |   33 ++++++++++++++++++++++++++++++---
>  fs/nfsd/nfs4state.c        |   10 ++++++++++
>  include/linux/nfsd/state.h |    3 +++
>  3 files changed, 43 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index 5823b9a..6f1ca49 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -43,6 +43,7 @@
>  #include <linux/sunrpc/xdr.h>
>  #include <linux/sunrpc/svc.h>
>  #include <linux/sunrpc/clnt.h>
> +#include <linux/sunrpc/svcsock.h>
>  #include <linux/nfsd/nfsd.h>
>  #include <linux/nfsd/state.h>
>  #include <linux/sunrpc/sched.h>
> @@ -52,16 +53,19 @@
>  
>  #define NFSPROC4_CB_NULL 0
>  #define NFSPROC4_CB_COMPOUND 1
> +#define NFS4_STATEID_SIZE 16
>  
>  /* Index of predefined Linux callback client operations */
>  
>  enum {
> -        NFSPROC4_CLNT_CB_NULL = 0,
> +	NFSPROC4_CLNT_CB_NULL = 0,
>  	NFSPROC4_CLNT_CB_RECALL,
> +	NFSPROC4_CLNT_CB_SEQUENCE,
>  };
>  
>  enum nfs_cb_opnum4 {
>  	OP_CB_RECALL            = 4,
> +	OP_CB_SEQUENCE          = 11,
>  };
>  
>  #define NFS4_MAXTAGLEN		20
> @@ -70,15 +74,22 @@ enum nfs_cb_opnum4 {
>  #define NFS4_dec_cb_null_sz		0
>  #define cb_compound_enc_hdr_sz		4
>  #define cb_compound_dec_hdr_sz		(3 + (NFS4_MAXTAGLEN >> 2))
> +#define sessionid_sz			(NFS4_MAX_SESSIONID_LEN >> 2)
> +#define cb_sequence_enc_sz		(sessionid_sz + 4 +             \
> +					1 /* no referring calls list yet */)
> +#define cb_sequence_dec_sz		(op_dec_sz + sessionid_sz + 4)
> +
>  #define op_enc_sz			1
>  #define op_dec_sz			2
>  #define enc_nfs4_fh_sz			(1 + (NFS4_FHSIZE >> 2))
>  #define enc_stateid_sz			(NFS4_STATEID_SIZE >> 2)
>  #define NFS4_enc_cb_recall_sz		(cb_compound_enc_hdr_sz +       \
> +					cb_sequence_enc_sz +            \
>  					1 + enc_stateid_sz +            \
>  					enc_nfs4_fh_sz)
>  
>  #define NFS4_dec_cb_recall_sz		(cb_compound_dec_hdr_sz  +      \
> +					cb_sequence_dec_sz +            \
>  					op_dec_sz)
>  
>  /*
> @@ -135,13 +146,19 @@ xdr_error:                                      \
>  		return -EIO; \
>  	} \
>  } while (0)
> +#define COPYMEM(x, nbytes) do {                \
> +	memcpy((x), p, nbytes);                \
> +	p += XDR_QUADLEN(nbytes);              \
> +} while (0)
>  
>  struct nfs4_cb_compound_hdr {
> -	int		status;
> -	u32		ident;
> +	/* args */
> +	u32		ident;	/* minorversion 0 only */
>  	u32		nops;
>  	__be32		*nops_p;
>  	u32		minorversion;
> +	/* res */
> +	int		status;
>  	u32		taglen;
>  	char		*tag;
>  };
> @@ -402,6 +419,15 @@ static struct rpc_clnt *setup_callback_client(struct nfs4_client *clp)
>  	addr.sin_family = AF_INET;
>  	addr.sin_port = htons(cb->cb_port);
>  	addr.sin_addr.s_addr = htonl(cb->cb_addr);
> +	if (cb->cb_minorversion) {
> +		BUG_ON(cb->cb_minorversion != 1);

Is this really a likely mistake?  Let's just drop this BUG_ON().

--b.

> +		args.bc_sock = container_of(clp->cl_cb_xprt, struct svc_sock,
> +					    sk_xprt);
> +	}
> +
> +	dprintk("%s: program %s 0x%x nrvers %u version %u minorversion %u\n",
> +		__func__, args.program->name, args.prognumber,
> +		args.program->nrvers, args.version, cb->cb_minorversion);
>  
>  	/* Create RPC client */
>  	client = rpc_create(&args);
> @@ -441,6 +467,7 @@ static int do_probe_callback(void *data)
>  	put_nfs4_client(clp);
>  	return 0;
>  out_release_client:
> +	dprintk("NFSD: synchronous CB_NULL failed. status=%d\n", status);
>  	rpc_shutdown_client(client);
>  out_err:
>  	dprintk("NFSD: warning: no callback path to client %.*s: error %d\n",
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index ad30039..61d5c66 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -651,6 +651,8 @@ static inline void
>  free_client(struct nfs4_client *clp)
>  {
>  	shutdown_callback_client(clp);
> +	if (clp->cl_cb_xprt)
> +		svc_xprt_put(clp->cl_cb_xprt);
>  	nfsd4_release_respages(clp->cl_slot.sl_cache_entry.ce_respages,
>  			     clp->cl_slot.sl_cache_entry.ce_resused);
>  	if (clp->cl_cred.cr_group_info)
> @@ -1391,6 +1393,14 @@ nfsd4_create_session(struct svc_rqst *rqstp,
>  		cr_ses->flags &= ~SESSION4_PERSIST;
>  		cr_ses->flags &= ~SESSION4_RDMA;
>  
> +		if (cr_ses->flags & SESSION4_BACK_CHAN) {
> +			unconf->cl_cb_xprt = rqstp->rq_xprt;
> +			svc_xprt_get(unconf->cl_cb_xprt);
> +			unconf->cl_callback.cb_minorversion =
> +				cstate->minorversion;
> +			unconf->cl_callback.cb_prog = cr_ses->callback_prog;
> +			nfsd4_probe_callback(unconf);
> +		}
>  		conf = unconf;
>  	} else {
>  		status = nfserr_stale_clientid;
> diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
> index 8762843..6bdf0d5 100644
> --- a/include/linux/nfsd/state.h
> +++ b/include/linux/nfsd/state.h
> @@ -203,6 +203,9 @@ struct nfs4_client {
>  	struct nfsd4_slot	cl_slot;	/* create_session slot */
>  	u32			cl_exchange_flags;
>  	struct nfs4_sessionid	cl_sessionid;
> +
> +	/* for nfs41 callbacks */
> +	struct svc_xprt		*cl_cb_xprt;	/* 4.1 callback transport */
>  };
>  
>  /* struct nfs4_client_reset
> -- 
> 1.6.2.1
>